The Nemo Cosmo is a lightweight, two-person mattress that is warm enough for three-season use and decently comfortable for an air mattress. The integrated foot pump makes for easy inflation, but you will want to practice deflation and storage before you hit the road to master the origami required to get it back in the stuff sack. The full inflation height is only three inches high, a little thin to protect from rocks and sharp ground, especially for side sleepers. But if you have very little space to store your camping mat, this one packs up quite small.
NEMO Cosmo 3D Insulated Review
Cons: Thin, not super warm
Manufacturer: NEMO Equipment
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Our Analysis and Test Results
We tested the double version of the Nemo Cosmo, which is an insulated air mattress that is big enough for two. It pumps up with an integrated foot pump but requires serious skills to fold it back up so that it fits in the stuff sack. It is impressively small, however, when you get it rolled up.
The Nemo Cosmo is an insulated air mattress that inflates to about three inches high. Air mattresses are always less comfortable than foam, primarily because they tend to feel bouncy, which is extra noticeable with two people sharing a mattress. The double version that we tested is 50 inches wide, and we found it to be fairly comfortable for an air mattress, even with two people. Movement can still be felt, but the narrow baffles and low height seem to work together to make the mattress more stable than the average air mat.
It has one micro-adjustment valve to get the right amount of inflation. Because it is only three inches high, we noticed that it was easy to get too soft, to the point where we felt the ground underneath, especially side sleepers. Too much inflation, however, increased the bounciness. It is worth noting that Nemo claims this mattress to be three and a half inches high, which is only the case in the large baffle at the head of the mat. This is not large enough for a pillow but does keep pillows from sliding off the top edge of the pad. The material is nylon and reasonably soft should your skin end up next to it. It makes the high-pitched whine of nylon when rubbed, especially when sleeping bags are moving around on top of it, though it isn't overly loud to sleep on.
Ease of Use
The Cosmo uses an integrated foot pump that is quite easy to use, assuming you have a place to stand-up to use it. It was a bit awkward in a truck bed, and also in a shorter tent, though it can also be pumped by hand. Full inflation can be achieved in a couple of minutes.
Deflation is quite easy, with two massive valves at the foot of the mattress that rapidly dump most of the air. After that, however, things get confusing. There are definitely some tricks to folding and storing the Cosmo. Our testers figured it out after a couple of tries, but there is also a video on the Nemo website to make this easier. All of the air needs to be pushed out of the foot pump, and then there are a whole series of folds. This is not the easiest mattress to get back into a stuff sack.
The R-value of air mattresses is notoriously low, and insulation is critical to making these usable beyond warm nights. The Cosmo is insulated with a layer of Primaloft, bringing its R-value to 3.3; this is not warm enough for winter but offers enough insulation to keep you comfortable when shoulder season temps dip into the 40s.
Our testers slept in the back of a truck as well as in a tent and found it to be acceptably warm. Nemo indicates that it can be used to 15 degrees Fahrenheit, and while we were not able to test at that temperature, we believe this mat used below freezing would only be adequate for those that sleep extremely warm and have a very warm sleeping bag. You can see the Primaloft inside the deflation valves, and it is quite surprising that such a small amount of insulation makes a difference! It adds very little bulk while adding significant warmth.
Campers who sleep out in climates where the temperature fluctuates greatly, or who camp into the colder months may want to look at warmer options, but for three-season use, the Cosmo is worth a look.
The Cosmo is a relatively lightweight two-person mattress, though not the warmest or lightest in our test. It is not exactly a beast at 4.36 pounds, but it is pretty heavy for backpacking. However, we can imagine uses where it would be a nice, lighter weight option such as a canoe trip. It just fits in the back of a van or pick-up bed, making it a good choice for trips where space is at a premium.
The Cosmo packs up to a pretty small little package when you consider that it is a two-person mattress. One difficulty with a two-person mattress is that the weight can't be distributed as two single mattresses can. But for those committed to sharing who also don't have space for a larger mattress, this has an impressive, packed size.
If you really want a two-person mattress, the Cosmo is a pretty comfortable, fairly warm, and lightweight option. The packed size is impressive. While it is relatively expensive, it is cheaper than buying two single mattresses. If space is a primary concern, this mattress is a good value.
The Nemo Cosmo is pretty good in a lot of ways, and maybe that is enough for someone looking for a two-person mattress that rolls up into a small package.
— Laurel Hunter